Income Taxes Income Tax Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate [Line Items]
Statutory U.S. Federal Tax Rate									35.00%
Expected income taxes									$ 11,823	$ 9,006	$ 8,650
Tax-exempt income from bank owned life insurance									235	0	0
Other tax exempt income									(1,577)	(1,103)	(954)
Nondeductible interest expense									21	11	10
State taxes, net of federal taxes									1,628	1,264	1,505
Other items									280	41	43
Effect of marginal tax rate									0	(1)	0
Total	$ 3,863	$ 2,812	$ 2,624	$ 2,641	$ 2,584	$ 1,979	$ 2,352	$ 2,303	$ 11,940	$ 9,218	$ 9,254